Open-hearth furnace



July 1, 1930. G. L. DANFORTA. JR 1,769,494

OPEN HEARTH FURNACE 'Original Filed Sept. 26, 1921 4 Sheets-Sheet 1 July1, 1930. G. L, DANFORTH, JR 1,769,494

OPEN HEARTH FURNACE l original Filed sept. 2e, 1921 4 sheets-sheet 2 Jlyl, 1930. G. l| DANFORTH, JR

OPEN HEARTH FURNACE original Filed sept. 2e, 1921 4 Shee'ts-Sheet 3eoffge LmfO/"Z/Z JK,

July 1, 1930. G. L. DANFORTH, JR 1,769,494

" OPEN HEARTH FURNACE original Filed sept. 2s, 1921 4 sheets-sheet 4Patented July4 l, 1930 UNITED STATES PATENT OFFICE GEORGE L. DANFORTH.,JR., OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIIGN- HENTS, TO OPENHEARTH COMBUSTION COMPANY, OF CHICAGO, ILLINOIS, A.

CORPORATION OF DELAWARE OPEN-Emma rUnNAcE I Original application filedSeptember 28, 1921, Serial No. 503,241. Divided and this application ledy A April 4, 1930. Serial No. 441,542.

This inventionrelates to a new and improved open hearth furnace, andmore particularly to a construction adapted to so direct the enteringgases and air in an open hearth furnace as to produce a quick burningand intensely hot llame adapted to provide Working heat adjacent thefull surface of the metal inthe furnace, and further adapted to providea' large' port area through which to exhaust the products of combustion.

'This application is a division of my copendin application Serial No.503,241, filed Septemel" 26, 1921.

My invention comprises an improvement in that portion of-an open hearthfurnace be- -tween the ports and the bath or melting chamber, and theremainder of the furnace and its appurtenances may be of any usualconstructiom 'As is well known in open hearth practice, the furnace isdouble-ended a'nd reversible, and is provided at each end with gas orair ports' which serve upon the outgolng endto carry `off the productsof combustion. In certain types of these fur-y naces burning producer orlike gases, these incoming gases are passed through regenerativechambers and are thus pre-heated. The incoming air is pre-heated in .asimilar manner and the heat of the furnacev flame is correspondinglyincreased. It is highly desirable in such furnaces to provide a short,quick llame which is directed toward the metal in the bath and whichdoes not extend to the outgoing end of the furnace. However, in actualpractice, since the same portsserve both to introduce the air and gasand to carry oi' the products of combustion, the latter function hasbeen largely the determining factor as regards the size of ports. Thisis for the reason that the products of combustion are of considerablygreater volumethan the incoming air and gas.

To secure a short, nick flame, it is essential that there be a ,quickand thorough mix,- ture of the incoming air and gas. It is impracticalto secure such a mixture and liame when the air and gas ports are of theusual comparatively large area. Endeavors are made to secure this quickmixture with such ports by surrounding the gas stream upon its sides andtop with the air stream. However, theintermixture in general occursgradually as the gas is passed across the furnace, the lighter glasgradually rising and intermingling wit the heavy air, combustion thusgradually taking place.

Endeavors have been made to secure a quick mixture and short llame bymeans of using comparatit'ely smalllair and -gas ports and providingauxiliary orts for carrying 'oil' the products of com ustion. ln suchconstructions, dampersgare provided to close the auxiliary passages u onthe incomin end of the furliacejjg.V The Iaddition of auxilg iary portsand up es unduly complicates the structure and this is particularly truein the usual type of furnace burning producer or similar gases. In suchfurnaces ,-as generallyconstructed, a single gas'uptake and port isflanked by anv air uptake and port upon each side thereof. All theseports are essential'tothe operation of' a furnace upon the `incomingend, although as has been stated, the port area is increased'over thatnecessary for the incoming air Aand gas in order to be of a sizeadequate 'to take care of the productsof combustion.

It is an object of the present invention to provide means locatedintermediate the ports and the furnace chamber which means are adaptedto vary the edective passage area between the vports and chamber.

It is a further object to provide means of this character which areadjustable to provide the full port area for handling the prod'- uctsofcombustion. A

It is an additional object to provide means which may be readillnstalledwithout undue modificationv `'0 the existing furnace structure.

It is also an object to provide a device which is relatively 'simple indesign, construction and operation.

Other and further objects will appear as the description proceeds.

Broadly my invention cbmprises the interposition of dampers between theports and furnace chamber, these dampers being adjustable-,to vary theeffective passage area. I have illustrated certain preferredembodishowing a portion of the furnace roof piv-` ments of my inventionin the accompanying drawings, in which- Figure 1 is a fragmentary,longitudinal section of an open hearth furnace having one form of myinvention applied thereto;

Figure 2 is a horizontal section of the form shown in Figure 1;

Figure 3 is a view similar to Figure 1 but showing a form of devicehaving a single, di agonally movable damper;

Figure 4 is a horizontal section of the form shownin Figure 3;

Figure 5 is a View similar to Figure 1 but showing a form of the devicehaving a sin,- gle, arcuately movable damper;

Figure 6 is a horizontal section of the form shown in Figure 5;

Figure 7 is a view similar to Figure 1 but oted to act as a damper; and

Figure 8 is a horizontal section of the form shown in Figure 7.

In the form of construction shown in Figures 1 and 2, the gas-uptake 40terminates in a relatively wide gas port 41.A The air uptakes 42 joinat48 above the gas port and the effective air port is located entirelyabove the gas port. In this form, the single damper 44 is passed throughwater-cooled guideways 45 in the roof. The damper is handled by means ofthe cable 46. Upon the outgoing end, it will be completely drawn up intothe roof and upon the incoming end, it will be lowered suiiciently toproperly limit the incoming p ort area and to direct the air stream intothe gas stream. Y

In thegform of construction shown in Figures 3 and 4, the central gasuptake 51 leads to the gas port 52. The llateral air uptakes 53discharge upon either side of the gas uptake. The furnace walls aredeflected inwardly somewhat at 54 and thus direct the air streamslaterally toward the gas. stream.

` This formation of the wall, however, is not suicient to obstruct theoutgoing gases. The sliding damper 55 is carried in the inclinedwater-cooled guideways 56 and is handled by cable 57. In its upperposition, the damper is housed in the box 58. A flange 59 upon thedamper interlits with a flange 60 upon the box to preventpassage ofgases into the box when the damper is lowered. This damper when-.loweredlimits the passage area and forces thenixture of the air and gas due tothis. restrictionin area. On the outgoing end, it israisedand permitsthe full area of the ports to be effective for carrying off the productsof combustion.

The form of device shown in Figures 5 and 6 is quite similar to that ofFi es 3 and 4,

- the modification being that t e damper is arcuate in form and isrotated instead of sliding in guideways. This arcuate damper 61 iscarried by the frame 62 which latter is rotatable about the shaft 63.Rotation of the frame about this shaft serves to swing the damperupwardly out of the furnace and into the box 64. Flanges 65 on thedamper frame interfit with flanges66 upon the lower part of the box topreventthe passage of gases into the box when the damper is down. In theform of device shown 1n Figures 7 and 8 the gas uptake 71 is flankedbythe air 'i forward part of the damper vis provided with an upwardlyextending flange 76 which serves to prevent the passage of gases betweenthe forward edge of the damper and the roof when the damper is inlowered position.

These several forms of construction which I have shown all serve torestrict the effective passage area between the ports and the fur naceupon the incoming end of the furnace. They thus cause a quick minglingof air and gas and a short flame upon the incoming end and furtherpermit the ready discharge of the products of combustion through thefull port area. Other and further modifications Y uptakes 7 2. A portionof the furnace roof' i aov of my construction may be made and it is myintention to cover all variations coming within the spirit and. scope ofthe appended claims.

I claim:

l. In an open hearth furnace, a hearth having its-end walls at each endsloping towards each other to a port of lesser Width and height than thecross sectional dimensions of the hearth, a chamber behind each port ofgreater width than the width of the port, and having its walls slopingtowards the port, suitable connections for the delivery of air and fuelbehind each port, whereby as said air and fuel travel towards the porttheir velocity is increased with correspond ing improvement of mixture,a vertically movable damper in the upper portion of each port servingvto close said upper portion, and means for adusting each dampervertically under the control of the operator, substantially asdescribed.

2. In an open hearth furnace, a hea'th havingl its end walls at each endsloping towards each other to a port of lesser width than the crosssectional dimensions of the hearth, a. chamber behind each port ofgreater width than the Width of the port, suitable and fuel forcombustion through each port, l

trol of the operator, substantially as described.

3. In an open hearth furnace, a hearth, a port at each end of the hearthof smaller size than the cross sectional dimensions of the hearth, achamber behind each port of greater width than the Width of the port,suitable connections for the delivery of air and fuel behind each portwhereby as said air and fuel travel towards the port their velocity isincreased with corresponding improvement of mixture, a verticallymovable damper in the upper portion of each port serving to close saidupper portion, and means for adjusting each damper vertically under thecontrol of the operator, substantially as described.

4. In an open hearth furnace, a hearth, a port at each end thereof, achamber behind each port having its roof sloping downwardly towards theport, means for delivering air a vertically movable damper 1n the upperportion of each port serving to close said upper portion, and means foradjusting each damper vertically under the control of the operatorwhereby the fiame emerging from each port is compelled to pass beneaththe damper thereof, and whereby the operation of said llame maybeadjusted by an adjustment .of the damper, substantially as described.

5. In an open hearth furnace, a hearth, a port at each end thereof, achamber behind each port, means for delivering air and fuel forcombustion through each port, avertically movable damper in the upperportion of each port serving to close said upper portion, and means foradjusting each damper vertically under the control of the operatorwhereby the flame emerging from each port is compelled to pass beneaththe damper thereof, and whereby the operation of said flame may beadjusted by an adjustment of the damper, substantially as described.

6. In an open hearth furnace, a hearth, a port at each end thereof, achamber behind each port, means for delivering air and fuel forcombustion through each port, a damper for each port, and means foradjusting each damper under the control of the operator, substantiallyas described.

7. In an open hearth furnace, a hearth, a port at each end thereof, achamber behind each port, and a vertically adjustable damperworkingdownwardly with respect to each port, the roof of each chamberslo ing down towards its port at an angle of su stantially 30 to thehorizontal, substantially as described.

8. An end construction for a regenerative open hearth furnace having athroat leading into the combustion chamber through which fuel may beintroduced or products of combustion may escape, and means for varyingthe effective area of the throat including a damper extendingtransversely of the throat from one side wall to the other and movableinto or out of the throat through an aperture in the furnace roof.

Signed at Chicago, Illinois, this 1st day of April, 1930.

GEORGE L. DANFORTH, JR.

